Facile Synthesis of Nanofibrous Polyaniline Thin Films for Ammonia Gas Detection

Polyaniline (PANI) nanofibers have been synthesized by in-&!blank;situ chemical oxidative polymerization of aniline monomer. The synthesized nanofibrous PANI was deposited as a thin film on a glass substrate by using dip-coating technique. The deposited thin films of PANI were characterized for their structural, morphological, and compositional studies using x-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), and x-ray photoelectron spectroscopy (XPS). The XRD patterns reveal the amorphous nature of deposited PANI thin films. FE-SEM micrographs exhibited the interconnected nanofibrous network of the PANI. TEM micrographs show the detailed structure of nanofibrous PANI having an average diameter of 45 nm and the selected-area electron diffraction (SAED) pattern reveals the amorphous nature. The prepared PANI thin films were investigated for ammonia (NH 3 ) gas sensing performance. The possibility of PANI thin films being used as sensors was verified in terms of sensitivity, response-recovery time, selectivity, and stability by varying the NH 3 gas concentration. The optimized PANI thin-film gas sensor showed a highest sensitivity of 29.30% at room temperature with stable response even after 45 days with 87% retention of stability. The gas-sensing results suggested the PANI nanofibrous sensor possess an excellent response for NH 3 gas even at low concentrations of 10 ppm.